Vacuum Tubes

1. A cold cathode diode is used as _________ tube.

1. a rectifier
2. a regulating
3. a power-controlled
4. an amplifying

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2. A directly heated cathode has _________ warm-up time

1. zero
2. large
3. small
4. very large

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3. A grid controlled vacuum tube acts as

1. an amplifier
2. a controlled switch
3. a rectifier
4. an oscillator

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4. A hard tube is defined as a tube with

1. a tungsten filament
2. a gas in the envelope
3. a metal envelope
4. no gas in the envelope

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5. A pentode is a _________ device.

1. constant current
2. linear
3. constant voltage
4. bilateral

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6. A thyratron can be used as

1. an oscillator
2. a controlled switch
3. an amplifier
4. an attenuator

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7. A triode is normally operated with control grid at _________ potential with respect to cathode.

1. positive
2. high positive
3. zero
4. negative

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8. A tube tester is used to check a triode's transconductance, which is the ratio of

1. a small change in cathode current to the corresponding small change in grid current
2. a small change in plate current to the corresponding small change in grid current
3. a small change in plate voltage to the corresponding small change in plate current
4. a small change in plate voltage to the corresponding small change in plate current

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9. A vacuum diode acts as a _________ switch.

1. bidirectional
2. unidirectional
3. controlled
4. omnidirectional

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10. A vacuum diode acts as a rectifier because of its _________ conduction.

1. unidirectional
2. bidirectional
3. isotropic
4. omnidirectional

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